(Oceanis 373) Water drainage from starting battery spot to main bilge pump reservoir

Jan 23, 2026
2
Beneteau 373 Austin
Oceanis 373 2005. I have a leak and water collects in a reservoir where starting battery is located, and in a smaller reservoir on the right And left from the engine, and I was surprised that these reservoirs are not connected to the main bilge pump reservoir and water just sticks there creating a safety risk.

Is it normal that starter battery "reservoir/section" is not connected to the main bilge pump reservoir and how to fix it? See the picture and video.
 

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jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
23,920
CAL 35 Cruiser #21 moored EVERETT WA
I do not know your boat. Generally, the bilge is connected via weep holes in the stringers and bulkheads. These can become blocked by gunk and may need to be cleaned.

There is a good reason for the battery box to be separated from the bilge. Battery acid from overcharged batteries that boil over can become contained in the battery box. Wear protective glasses and gloves when dealing with any fluids in a battery box.

I would source the fluid that is draining into the battery box and stop it, rather than trying to create a drain to the rest of your bilge.
 
Feb 21, 2010
355
Beneteau 31 016 St-Lawrence river
Your picture shows water in the battery area. It also shows the other basin connected to it… this is under the engine and has some oil in it. Were all this to drain to the main bilge and be pumped out you would be in trouble! Pumping oil overboard isn’t lightly regarded anywhere.
I would clean all this out (including the other basin), find the leak and fix it.
A dirty but very gratifying job. (Been there)
Pierre
 
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Likes: vallkor
May 17, 2004
5,940
Beneteau Oceanis 37 Havre de Grace
On the 37 (the next generation after the 373) there are limber holes from that area into the bilge. The pan under the engine, between the stringers that hold the engine mounts, is separate and isolated to contain any engine spills. The battery box itself should contain any acid that spills over from the battery. My guess is there are limber holes somewhere in the forward part of that compartment that have gotten plugged from debris over time.
 
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Likes: BigEasy
Jan 23, 2026
2
Beneteau 373 Austin
My guess is there are limber holes somewhere in the forward part of that compartment that have gotten plugged from debris over time.
Thanks! I checked multiple times and didn't find wholes that connects battery section with bilge pump :( I hope someone with similar 373 can confirm it is the case for them too.
 
Jun 21, 2004
3,057
Beneteau 343 Slidell, LA
Oceanis 373 2005. I have a leak and water collects in a reservoir where starting battery is located, and in a smaller reservoir on the right. Is it normal that starter battery "reservoir/section" is not connected to the main bilge pump reservoir and how to fix it?
Have a similar configuration on my 06 Oceanis 343. Years ago, I had a leaking thru hull fitting for shaft seal cooling water & water pooled in that dedicated battery space. Had to vacuum it to empty. Suggest you vacuum & dry. Likely source(s) are shaft seal, shaft seal cooling water nipple, both thru hull fittings & components for raw water & shaft seal cooling water, exhaust mixing elbow, water pumps, & hoses.
 
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